1. Field of the Invention
This invention relates to stands that hold a bicycle stationary for exercise and provide rolling resistance that simulates bicycle riding.
2. Description of Prior Art
Prior exercise stands for bicycles provide rolling resistance of various types, each of which has disadvantages. Frictional resistance units that are manually controlled do not provide resistance that increases realistically with speed. Thus, adjustment may be required at higher speeds, distracting the user. Air impellers are noisy and have no inherent momentum, so they require a separate heavy flywheel for realistic momentum. Air impellers do not provide high enough resistance for hill training, in which the rider stands on the pedals for maximum force. The advantage of air impellers is that they do not overheat. Fluid impellers are less noisy, but are expensive because they required a fluid-tight chamber with axle seals, fluid fill means, etc. Fluid impellers have a strong tendency to over-heat and leak fluid. Thus, they are not highly practical. They also have inadequate resistance for hill training. The impeller must turn extremely fast to be effective, so the tire-contact roller must have a small diameter. This tends to cause tire slippage, squealing, and wear. High impeller rpm requires dynamic balancing for vibration-free operation, which is prohibitively expensive. Fluid impeller units often generate vibration during use. They need a separate flywheel for momentum, which adds expense, but making the impeller heavy enough for a flywheel would be even more expensive. Magnetic resistance units use eddy currents in magnetic fields between moving and stationary permanent magnets. Magnetic units tend to have less resistance at higher speeds, which is the opposite of the desired resistance curve for realistic ride simulation.
Prior exercise stands for bicycles provide various means for mounting a bicycle on the stand. Commonly the rear axle is clamped between opposed cups on the stand. The opposed cups must be separated for insertion and removal of the bicycle rear axle, and moved toward each other to clamp the axle firmly between them. This has been previously done by mounting at least one of the cups on a threaded shaft that can be turned to move the cup toward or away from the opposite cup. However, it is very awkward to hold a bicycle in position with one hand while turning a knob near the rear axle. Another approach is providing a hand-lever that moves one cup toward or away from the opposite cup. This is faster, but still requires one hand on the lever, leaving only one hand to hold the bicycle in position. One series of prior bicycle stands (Minoura) offered foot operated clamping via rod linkages to a plunger the moves one of the cups. However, it was not successful in the market due to inadequate force transmission, and allowance of play. This type of linkage is also expensive to produce and is subject to damage.
Some prior exercise stands for bicycles do not provide full adjustability for different sized bicycles. Others provide adjustability, but hold the rear tire of smaller bicycles off the ground. Small bicycles mounted in these stands will not be level unless the front tire is also raised off the ground. Holding one or both of the tires off the ground makes the bicycle difficult to mount for the small rider, and gives an unnatural ride feeling.
U.S. Pat. No. 4,941,651 shows a manually controlled frictional resistance unit and a manual clamping lever
U.S. Pat. No. 5,944,637 shows a fluid impeller resistance unit
U.S. Pat. No. 6,042,517 shows a magnetic resistance unit
U.S. Pat. No. 5,522,781 shows a stand design that holds smaller tires off the ground
U.S. Pat. No. 5,145,478 shows a stand with foot pedal and rod linkage to the clamp
Other examples of related prior art are listed on the front page of the patent. The present invention overcomes the above shortcomings of the prior art.
The objectives of the present invention are provision of an exercise stand for a bicycle with realistic ride resistance that increases with speed, provides little or no resistance during start-up, provides completely solid support of a bicycle without play, provides quick and easy mounting and removal of a bicycle from the stand, provides full adjustability of the stand for all sizes of bicycles, supports the rear tire of any size bicycle no more than xe2x85x9 inch off the ground, provides maximum durability, minimum maintenance, minimum cost, minimum weight, and minimum folded size for shipping.
The objectives of the present invention are achieved with a first support arm 2 fixed to a base 1, a second support arm 3 pivotally attached to the base. A cam operated by a foot lever 6B controls the pivot position of the second arm, moving it toward or away from the first arm to clamp or release the rear axle of a bicycle between the arms. An inward-facing cup 2A, 3A on each arm holds the ends of the bicycle axle. The cups are vertically adjustable on the arms. Other adjustments optimize the frame for any size bicycle wheel. A resistance unit 7 attached to the base has a tire contact roller 7E driven by the rear tire of a bicycle. A centrifugal clutch in the resistance unit urges a rotating friction plate against a stationary friction pad, providing ideal ride resistance ranging from zero at start-up to full hill-climbing resistance that supports a rider standing on the bicycle pedals at maximum output.